A 1x2 3U Gridfinity bin that stores two specific camera levels that mounts in the camera shoe.
Specifically these two: https://www.amazon.com/FOTYRIG-Camera-Olympus-Digital-Cameras/dp/B07DPK3ZVH?crid=1025JITHD2CS7&keywords=camera+hot+shoe+level&qid=1696696952&sprefix=camera+hot+shoe+level,aps,169&sr=8-8